SYLVIS - Reigning Masters and US Open champion Jordan Spieth ratcheted up his preparation for next week's British Open by firing a seven-under-par 64 in Friday's second round of the PGA John Deere Classic. While fellow American Justin Thomas followed a 63 with a 67 to seize the overall lead, attention focused on Spieth. World number two Spieth found 10 of 14 fairways and reached 13 of 18 greens in regulation in making six birdies and an eagle against a lone bogey to move into a share of 16th after an opening 71 at the event he won in 2013 to secure a place on the PGA Tour. "Today was a big day," Spieth said. "I made a huge step forward today based on how I felt yesterday. I wasn't feeling good about my game. Ultimately, this was a big day for me in my preparation for next week."